Wood is degraded by microorganisms, particularly fungi and bacteria, which contribute to degradation by creating environmental conditions favorable to further decay or consumption by larger organisms, such as insects or marine borers. Wood preservation methods attempt to arrest degradation by these microorganisms. Current and near term wood preservation techniques suffer from limitations such as wood treatability, broad spectrum efficacy, affordability, and environmental safety/human toxicity. For example, some of the most effective treatments use arsenic containing compounds such as chromated copper arsenate (CCA) and may no longer be used in much of the world because of potential toxicity/environmental concerns. In addition, certain fungi have developed resistance to copper compounds.
Wood preservatives traditionally are classified as either oil-borne or waterborne depending on the type of solvent used. Waterborne preservatives are generally easy to apply, but leaching lowers efficacy of waterborne preservatives and increases environmental/safety burden. For example, boron-based waterborne preservatives are cheap and effective but leach easily, and some boron preservatives only rate for extremely narrow uses. Chromates, commonly used in wood preservatives, provide increased retention; however, chromates increase heavy metal toxicity of the preservative.
A water-soluble chemical formulation with a broad spectrum efficacy and high retention in the wood after application would provide a highly desirable preservative. According to the U.S. Department Of Agriculture's Forest Products Laboratory, wood preservatives must meet two broad criteria: “(1) they must provide the desired wood protection in the intended end use [i.e. efficacy in the end application], (2) they must do so without presenting unreasonable risks to people or the environment.” The embodiments described herein provide water-soluble, high retention, safe, and broad spectrum wood preservatives for multiple applications.